package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSON;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CashClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CashClient cashClient;

    /**
     * 根据id查询商铺信息
     * @param id
     * @return
     */
    @Override
    public Result queryById(Long id) {
        //缓存穿透
        /*Shop shop = cashClient
                .queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);*/
        //互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
        Shop shop = cashClient
                .queryWithLogicalExpire(id, CACHE_SHOP_KEY, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        //7.返回结果
        return Result.ok(shop);
    }

    /**
     * 缓存重建的线程池
     */
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    /**
     * 逻辑过期解决缓存击穿
     * @param id
     * @return
     */
/*    public Shop queryWithLogicalExpire(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //2.1存在，返回
            return null;
        }
        //3.命中需要判断过期时间，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //4.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //4.1未过期，直接返回店铺信息
            return shop;
        }
        //4.2已过期，需要缓存重建
        //5缓冲重建
        //5.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean islock = tryLock(lockKey);
        //5.2判断是否获取锁成功
        if (islock) {
            //5.3成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                //重建缓存
                try {
                    this.saveShop2Redis(id, 20L);
                    //TODO 再次检测缓存是否过期
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unlock(lockKey);
                }
            });
        }

        //5.4返回过期的商品信息
        return shop;
    }*/

/*    public void saveShop2Redis(Long id, Long expireSecond) throws InterruptedException {
        //1.查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusMinutes(expireSecond));
        //3.写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }*/

    /**
     * 更新商铺信息
     * @param shop
     * @return
     */
    @Override
    @Transactional
    public Result update(Shop shop) {
        if (shop.getId() == null) {
            return Result.fail("店铺id不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        //3.返回结果
        return Result.ok();
        /*Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        //更新数据库
        updateById(shop);
        //删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        return Result.ok();*/
    }

/*
    *//**
     * 获取锁
     * @param key
     * @return
     *//*
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    *//**
     * 释放锁
     * @param key
     *//*
    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }*/

    /**
     * 缓存击穿（互斥锁）
     * @param id
     * @return
     */
/*    public Shop queryWithMutex(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //存在，返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //3.判断命中的是否是空值
        if (shopJson != null) {
            //3.1返回错误信息
            return null;
        }
        //4. 实现缓存重建
        //4.1 获取互斥锁
        Shop shop = null;
        String lockKey = "lock:shop:" + id;
        try {
            boolean islock = tryLock(lockKey);
            //4.2 判断是否获取成功
            if (!islock) {
                //4.3失败，休眠
                Thread.sleep(50);
                queryWithMutex(id);
            }
            //4.4 成功，根据id查询数据库
            //查询redis
            shopJson = stringRedisTemplate.opsForValue().get(key);
            if (StrUtil.isNotBlank(shopJson)) {
                //存在，返回
                return JSONUtil.toBean(shopJson, Shop.class);
            }
            shop = getById(id);
            //模拟重建延迟
            Thread.sleep(200);
            //4.不存在，根据id查询数据库
            if (shop == null) {
                //5.数据库不存在，返回错误
                stringRedisTemplate.opsForValue().setIfAbsent(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            //6.存在，写入redis
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7.释放锁
            unlock(lockKey);
        }
        //8.返回结果
        return shop;
    }*/

    /**
     * 缓存穿透
     * @param id
     * @return
     */
    /*public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在直接返回
            Shop shop = JSONUtil.toBean(shopJson,Shop.class);
            return shop;
        }
        //判断命中的是否是空值
        if (shopJson != null) {
            //4.存在，但是是一个空值，直接返回错误信息
            return null;
        }
        //4.不存在，根据id查询数据库
        Shop shop = getById(id);
        //5.不存在，返回错误
        if (shop == null) {
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            //返回错误信息
            return null;
        }
        //6.存在，写入redis在返回
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回结果
        return shop;
    }*/
}
